1. Field of the Invention
This invention relates to a zoom lens barrel, and more particularly to a zoom lens barrel capable of close up photography.
2. Description of the Prior Art
A lens capable of photography up to a close up photography area only by a focusing operation may be said to be superior in quickness of photography because it permits continuous distance adjustment to be effected. However, in a zoom lens including a wide angle of view and a standard focal length, if the forward group lens thereof which effects distance adjustment is axially shifted excessively, deficiency of quantity of light and unsatisfactory lens aberrations occur in the wide angle area and therefore, very short distance photography (macro photography) is limited of itself. Therefore, in the lenses of such type, a change-over device for separating a magnification changing lens system from zooming by displacing such lens system to a position for macro photography has been provided and the focusing to a proximate object has been made possible after a change-over operation. However, such prior art is complicated in construction because there is provided therein a mechanism for axially shifting the entire lens system or for the macrofocusing of the magnification changing system. Also, such prior art involves two different operations of ordinary focusing and macrofocusing which are very confusing, and this leads to lack of quickness of photography.